First and foremost in the field, The Henna Page leads the way in information and research about henna. It hosts a forum for the henna community as well as the encyclopedia of henna and free henna patterns.

Another growing henna resource is the Henna Tribe. They also host a forum and offer free patterns.

If you're looking for fantastic artist on the west side of Michigan, go to Stroke of Luck Henna.

If you dig deep enough in amazon.com you'll find a trove of design and pattern books that are great inspiration for creating your own henna patterns.

One of my favorite online resources is about.com. In the body art section, it has several articles about henna.